Hypertension during pregnancy affects 5-8% of pregnancies in the United States and contributes to serious complications for both the fetus and mother. Hypertension may lead to pre-eclampsia, which can restrict fetal growth or trigger premature birth. The rate of pre-eclampsia has increased by nearly one-third during the past decade. One well recognized independent risk for hypertension is sleep-disordered breathing (SDB). This common and treatable, but usually undiagnosed sleep disorder often develops with excess body weight. Available literature suggests that substantial weight gain and other physiological changes during the short period of pregnancy may be associated with increased snoring, a well known marker for SDB risk. However, the prevalence of SDB in pregnancy is not well known, the best symptoms and signs to use as screens for its presence remain largely unstudied, and its relationships to maternal and fetal outcomes have never been explored in a large sample. The main goals of this revised application, therefore, are to determine the frequency of SDB symptoms and signs in a sample of women in the last trimester of pregnancy, and to assess whether such symptoms and signs may predict two key adverse outcomes, pre-eclampsia in the mother and small size for gestational age in the infant. In addition, we will show "proof-of-concept" that habitual snoring is associated with objective measures of respiratory events from polysomnography in a sample of pregnant women. Aim 1 will compare the cross-sectional frequencies of snoring and other SDB symptoms among 1400 third-trimester pregnant women and 200 non-pregnant women. Aim 2 will demonstrate the cross-sectional association, among the 1400 pregnant women, of simple physical airway and neck measurements with SDB symptoms. Aim 3 will use postpartum medical records of the 1400-subject cohort to assess the extent to which SDB symptoms and signs predict adverse pregnancy outcomes, in particular pre-eclampsia and low birth weight. As an exploratory aim, Aim 4, will test whether self-reported habitual snoring is associated with an increased number of respiratory events, as measured from a polysomnogram in 20 women with habitual and 20 women without habitual snoring. Such respiratory events are likely the presumed intermediary variable between SDB symptoms and outcomes. Results of this study could have important impact on public health. SDB will be implicated, for the first time in a large prospective study, as a risk factor for adverse maternal and infant outcomes. Clinicians will be given new, simple, and inexpensive screening tools to identify risk for these outcomes. Data generated in this initial study will provide critical justification for new research on next steps beyond screening, namely early SDB diagnosis and treatment during pregnancy -- as strategies to reduce pre-eclampsia and low birth weight. PUBLIC HEALTH RELEVANCE: Results from this study will have a major influence on public health. Sleep-disordered breathing will be implicated, for the first time in a large prospective study, as a risk factor for adverse maternal and infant outcomes and clinicians will be alerted to potential symptoms and signs that may identify a problem. This study will ultimately lead to the development of early intervention strategies to treat sleep disordered breathing during pregnancy which may ultimately reduce risk of adverse pregnancy outcome.